<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            box-sizing: border-box;
        }

        .content {
            display: inline-flex;
            flex-direction: column;
            padding-left: 50px;
        }

        .content>div {
            /* height: 100px;
            width: 500px;
            border: none; */
            /* border-top: 20px solid; */
        }

        .child {
            width: 440px;
            height: 5px;
            /* background-color: red; */
            margin-bottom: 50px;
            position: relative;
            z-index: 1;

            & .child-right {
                content: "";
                display: inline-flex;
                width: 60px;
                height: 60px;
                border-radius: 60px;
                background: linear-gradient(red 0%, blue 100%);
                position: absolute;
                top: 0;
                right: -30px;
                z-index: 0;
                padding: 5px 5px 5px 0;
                /* border: 5px solid; */
                /* border-left: none; */
                /* border-image: linear-gradient(red, blue) 5; */
                /* background: conic-gradient(from -90deg, red, blue); */

                /* linear-gradient(red 0%, blue 100%); */
                &::after {
                    content: "";
                    display: block;
                    width: 100%;
                    height: 100%;
                    background-color: #fff;
                    border-top-right-radius: inherit;
                    border-bottom-right-radius: inherit;
                }
            }


            /* border-top-right-radius: 500px;
            border-bottom-right-radius: 500px;
            background: conic-gradient(from -90deg, blue, rgb(55, 55, 255), rgb(255, 84, 84), red);
            padding: 6px 6px 6px 0;

            & .child-inner {
                width: 100%;
                height: 100%;
                background: #fff;
                border-top-right-radius: 50px;
                border-bottom-right-radius: 50px;
            } */
        }


        .child:nth-child(odd) {
            background-color: red;
        }

        .child:nth-child(even) {
            background-color: blue;
        }

        /* .content>div:nth-child(even) {
            border-left: 20px solid red;
            border-image: linear-gradient(to left, red, green);
            border-image-slice: 1;
        } */
    </style>
</head>

<body>
    <!-- https://segmentfault.com/q/1010000044600912
    横向U型步骤条有类似的组件？ -->
    <div class="content">
        <div class="child">
            <div class="child-right"></div>
        </div>
        <div class="child">
            <div class="child-left"></div>
        </div>
        <div class="child">
            <div class="child-right"></div>
        </div>
        <div class="child">
            <div class="child-left"></div>
        </div>
    </div>
</body>

</html>